Activation of the latent protein kinase, PKR, by extracellular stresses and triggering of resultant cellular apoptosis are mediated by the protein, PACT, which itself gets phosphorylated in stressed cells. We have analyzed the underlying biochemical mechanism by carrying out alanine-scanning mutagenesis of the PKR activation domain of PACT. Among the indispensable residues identified were two serine residues, whose phosphorylation was essential for the cellular actions of PACT. Two-dimensional… CONTINUE READING